When processing workpieces with a laser beam, it is mainly Gaussian laser beams that are used. This processing includes welding, cutting, melting, heating, erosion, marking, thermal joining. In the case of laser welding, in particular CO2 laser welding, a connection between workpieces to be welded is created via an energy input, defined by the laser beam, into the structure to be welded, by melting the two workpieces in the area irradiated by the laser beam, after which they re-solidify jointly after they have coalesced.
A keyhole (cannula) filled with metal vapor, through which the laser beam can penetrate deep into the workpiece and around which the melt is produced, is produced by the focused laser beam during deep-penetration laser welding. This narrow keyhole can produce instabilities in the melt which lead to eruptions and thus to a suboptimal weld seam.
Likewise, when welding thin sheets by heat conduction welding, in the case of sheets coated with other metals, the produced melt is not stable and, as a result of eruption, a reliable weld seam is prevented. Work has been done, in the case of welding, for example, zinc-plated sheets for the automotive industry, in which spacers are used to ensure that evaporations which occur do not blow the melt out of the weld seam. For example, small microbeads are introduced between the sheets to be welded prior to the welding in order to create this distance.